柴北缘—东昆仑地区造山型金矿床的三级控矿构造系统

不同等级体制的构造分别控制了柴北缘—东昆仑地区造山型金矿的区域、矿化集中区以及矿床和矿体的分布和产出。在一个次级大地构造单元或成矿带内,造山型金矿大多产于构造边界和/或深大断裂旁侧(即造山带构造边界和/或深大断裂是柴北缘—东昆仑地区造山型金矿的第一级控制构造)。发育在上述深断裂旁侧的大型剪切带,控制了矿化集中区或矿田范围内金化探异常和造山型金矿床的分布和产出,是柴北缘—东昆仑地区造山型金矿的第二级控制构造。上述大型剪切带派生的褶皱和断裂系统,是造山型金矿床的第三级控矿构造,它们控制了矿体的分布和产出,滩间山、大场金矿床是褶皱控矿的良好例证,而五龙沟金矿床则是与剪切带伴生的断裂-裂隙系统控矿的典型实例。相比之下,受控于褶皱的金矿床中矿体规模较大、空间上变化较小。上述造山带构造边界和/或深大断裂、大型剪切带和大型剪切带派生的褶皱和断裂系统主要是区域加里东和晚华力西—印支碰撞造山作用的产物,它们具有大致相同或互相联系的几何学、运动学和年代学特征,后者通常是前者的派生、低序次构造。因此,这3个不同级别的构造,构成了柴北缘—东昆仑地区造山型金矿床的控矿构造系统。

Three-order ore-controlling structural system of orogenic gold deposits in the northern Qaidam margin-East Kunlun region

The regional distribution and occurrence and distribution of mineralization concentration areas,ore deposits and orebodies of orogenic gold deposits in the northern Qaidam margin-East Kunlun region were controlled by structures of different orders.In a second-order tectonic unit and/or metallogenic zone,orogenic deposits mostly occur near the tectonic boundary and/or a deep fault,i.e.the tectonic boundary of an orogen and/or a deep fault is the first-order ore-controlling structure of orogenic gold deposits in the northern Qaidam margin-East Kunlun region.Gold geochemical anomalies and orogenic gold deposits in a mineralization concentration area or an ore field are controlled by a large-scale shear zone developed at the side of a deep fault mentioned above,which is the second-order ore-controlling structure of orogenic gold deposits in the northern Qaidam margin-East Kunlun region.Folds and fault systems derived from the above-mentioned large-scale shear zone are the third-order ore-controlling structure of orogenic gold deposits in the region,which control the occurrence and distribution of orebodies in ore deposits.The Tanjianshan gold deposit and Dachang gold deposit are typical examples for fold controls on mineralization,while the Wulonggou gold deposit is a typical example of controls of mineralization by the fault-fissure system association with the shear zone.In contrast with those gold deposits under control of the fault system,the orebodies in gold deposits controlled by folds are larger in size and less variable in space.The tectonic boundaries of orogens and/or deep faults,large-scale shear zones and folds and fault systems derived from the above-mentioned large-scale shear zones mainly resulted form the regional Caledonian and late Variscan-Indosinian collisional orogeny,and they have about the same or interrelated geometry,kinematics and geochronology,of which the latter are commonly structures of lower order derived from the former.Therefore,the three structures of different orders form an ore-controlling structural system of orogenic gold deposits in the northern Qaidam margin-East Kunlun region.